Different Degrees of Electron Delocalization in Mixed Valence Ru-Ru-Ru Compounds by Cyanido-/Isocyanido-Bridge Isomerism.

The two stable pairs of trimetallic compounds trans-[Cp*(dppe)Ru(μ-NC)Ru(dmap)4 (μ-CN)Ru(dppe)Cp*][PF6 ]n (1[PF6 ]n , n=2, 3; Cp*=1,2,3,4,5-pentamethylcyclopentadiene; dppe=1,2-bis-(diphenylphosphino)ethane; dmap= 4-dimethylaminopyridine) and trans-[Cp*(dppe)Ru(μ-CN)Ru(dmap)4 (μ-NC)Ru(dppe)Cp*][PF6 ]n (2[PF6 ]n , n=2, 3), which demonstrate cyanide/isocyanide isomerism, have been synthesized and fully characterized. 13+ [PF6 ]3 and 23+ [PF6 ]3 are the one-electron oxidation products of 12+ [PF6 ]2 and 22+ [PF6 ]2 , respectively. The results suggest that 1[PF6 ]3 is a class III mixed valence compound, whereas 2[PF6 ]3 might be an unusually symmetrical class II-III mixed valence compound composed of the two asymmetrical delocalized RuIII -NC-RuII mixed valence subunits.